Conventionally, for example, the following Patent Literature 1 discloses a configuration of a single photon avalanche diode (SPAD) which includes a first semiconductor layer that is a first buried layer having a first conductivity type, a second semiconductor layer having a second conductivity type opposite to the first conductivity type under the first semiconductor layer, in which the second semiconductor layer is buried in an epitaxial layer, and the second semiconductor layer is completely converted into a depletion layer by applying a bias voltage thereto.